The development of reliable thin, insulating barrier coatings for flexible ribbon cables and micro-electrodes used in biomedical implants has been a significant problem. Our preliminary tests have demonstrated the feasibility of using spin-on polyimide coatings for fabricating flexible ribbon cables with barrier properties suitable for long-term in Vivo applications. These tests used thin films of spin coated polyimides on flexible polyimide substrates (Kapton H(R)) with gold conductors between the substrate and coating materials. After almost 18 months of continuous exposure to isotonic saline solution at 37 degrees C, these coatings still show excellent dielectric barrier properties. Gas plasma polymer coatings provide excellent adhesion and have been used as "primer" layers for various conventional polymer films. These coatings can also be easily modified chemically and have shown to increase the biocompatibility of underlying substrates. Insulation coatings used in long term implants have to exhibit excellent adhesion for many years and also have to be biocompatible. In this proposal the combination of gas plasma coatings with spin-on polyimides will be developed for feasibility studies. We will explore feasibility of this approach for encapsulation for flexible implants with unsurpassed dielectric barrier properties as well as biocompatibility. PROPOSED COMMERCIAL APPLICATIONS: About 25 million people in the US alone have implants. A significant and growing portion of these implants are electronic or contain electronic device interfaces. Biomedical implants and flexible interconnecting cables used in long-term in vivo applications without triggering inflammatory cell responses have a great commercial potential. These implants and cables have to be protected with insulating barrier coatings to resist the penetration of biological fluids.